DESCRIPTION: Chronic otitis media (COM) is a common, chronic inflammatory condition affecting the middle ear and mastoid that can result in a conductive hearing loss of up to 60 dB. The main treatment for COM is surgical, consisting of tympanoplasty and mastoidectomy operations, with over 70,000 operations performed annually in the United States. Post-operative hearing results after such procedures are often unsatisfactory, especially when the ossicular chain is diseased or when the middle ear space remains poorly aerated. The long-term goal of this research proposal is to develop acoustical principles that can be used by otologists to improve and optimize the hearing results after tympanoplasty and mastoidectomy procedures. The PI proposes to combine measurements of physical function (e.g., sound pressure, ossicular motion, acoustic impedance) in a surgically-modified human temporal bone preparation with anatomical measurements of structure-function relationships of a reconstructed ear which can then be used by otologists to rationally modify current reconstructive techniques or to devise new techniques. This approach has worked well for the PI in characterizing type IV tympanoplasty, and has resulted in several simple but specific surgical recommendations to optimize post-operative hearing results. The proposed experiments have been designed to investigate the following specific issues: (1) To determine the effects of size of middle-ear air space on hearing results after tympanoplasty reconstruction; (2) To develop new types of middle-ear implants for improving post-tympanoplasty hearing results in non-aerated ears; (3) To define the critical structural characteristics of ossicular prostheses that determine hearing results after tympanoplasty reconstruction; and (4) To evaluate the role of resonance within canal-wall down mastoidectomy cavities in determining hearing results.